SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b6dab3c28c73cff57c1bda4cc435ee36de9589589960daba91e8ea50630e346' 
  AND token = 'yuCt09GjaRowKJgzyF+tbOEbZ/kqLUdVpU+M2IRFvPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}